Seznam abstraktů 2023: SEKCE B - PRŮMYSLOVÉ A ENVIROMENTÁLNÍ APLIKACE NANOMATERIÁLŮ

A range of technologies require the directed motion of nanoscale droplets on solid substrates. Such motion takes place in living matter too. A way of realizing this effect is by using gradient substrates which can induce uni-directional motion without requiring an external energy source. Here, we report on the results of extensive molecular dynamics investigations of droplets on surfaces with gradually changing rigidity, rugosity, or grafting density of the polymer brush coating which exhibit the effect of droplet propulsion in direction of the changing property (e.g., durotaxis from soft to stiff area on the substrate, or rugotaxis toward places with denser wrinkles). While durotaxis depends essentially on droplet adhesion and the stiffness gradient value, rugotaxis on wrinkled surfaces is most efficient on shallow substrates with small wavelength gradients, and moderate droplet adhesion to the substrate. Also brush coatings with steadily varying stiffness, or grafting density of the polymer chains, are found to provide optimal droplet motion for a selected combination of the governing parameters. Generally, we find that the driving force in durotaxis/rugotaxis phenomena is the steady gain in interfacial energy between the droplet and the substrate. We anticipate that our findings indicate further possibilities in the area of nanoscale motion without external energy supply.

In the last years‚ the search of novel and cost-effective catalysts to replace costly and scarce noble metals drove to explore a wide range of materials‚ such as transition metal dichalcogenides (TMDCs)‚ phosphides‚ carbides‚ nitrides among others [1]. Inspired by the first experimental evidences reported on the catalytic activity of MoS2 edge sites [2], an intense researching work has been devoted in exploring the catalytic properties of other 2-dimensional (2D) TMDCs‚ e.g. WS2‚ MoSe2‚ and MoTe2 [3-6]. 2D materials offer unique structural‚ optical and electronic properties as compared to the bulk counterparts. In addition‚ they show significant prospects as catalyst mainly due to the flake-like morphology with minimal thickness‚ high surface-to-volume ratio‚ and capability of surface functionalization and tuning the catalytically active edges sites [7]. Among the TMDCs materials‚ the catalytic properties of iron sulfide and its different phases‚ namely FeS2‚ Fe3S4 and FeS‚ have been largely overlooked and barely explored compared to other TMDCs‚ despite the relative low cost and toxicity and the high natural abundance of iron and sulfur.
Herein‚ we present 2-dimensional (2D) FeSx nanosheets of different sizes as an electrocatalyst towards hydrogen evolution reaction (HER) in alkaline media. The 2D FeSx nanosheets were synthesized by applying different numbers of Atomic Layer Deposition (ALD) cycles on TiO2 nanotube layers and graphite sheets as active supporting materials. The electrochemical results confirmed the electrocatalytic activity with an excellent long-term stability and an enhanced catalytic activity reflected by a noteworthy drop of the HER overpotential. Using a range of characterization techniques‚ it was unveiled that the origin of the enhanced catalytic activity was caused by the synergistic interplay between in situ morphological and composition changes experienced by the 2D FeSx nanosheets during HER. Under the application of a cathodic potential in alkaline media‚ it was observed that the original 2D FeSx nanosheets transformed to iron oxyhydroxide-iron oxysulfide core-shell nanoparticles‚ which exhibited a higher active catalytic surface and newly created Fe-based HER catalytic sites [8]. REFERENCES: [1] P. Yu et al‚ Nano Energy2019‚ 58‚ 244-276.; [2] T. F. Jaramillo et al Science (80-).2007‚ 317‚ 100-102.; [3] J. Bonde et al‚ Faraday Discuss.2009‚ 140‚ 219-231.; [4] J. C. McGlynn et al.‚ Nat. Commun.2019‚ 10‚ 4916.; [5] M. Motola et al.‚ Nanoscale2019‚ 11‚ DOI 10.1039/c9nr08753b.; [6] R. Zazpe et al.‚ Appl. Mater. Today2021‚ 23‚ 101017.; [7] S. H. Noh et al‚ J. Mater. Chem. A2018‚ 6‚ 20005-20014.; [8] R. Zazpe et al‚ ChemSusChem, 2023,16, e2023001.

Plasmonic nanoantennas represent advanced structures that allow sub-diffraction manipulation with light energy and its simultaneous focus below the diffraction limit. Gigantic focusing of light energy in the desired targeted place allows for the realization of several phenomena, such as plasmon-induced charge energy transfer of excitation/injection of so-called hot electrons. In turn, such phenomena have found a range of applications in the fields of medicine, sensorics, photovoltaics, and chemical transformation triggering. The main obstacle to greater use of plasmon-based nanoantennas is their complex preparation route and the resulting lack of ‘scalability’ of the structure.
In this work, we propose a simple and effective method for the preparation of plasmonic nanoantennas, in which the metal-insulator-metal (MIM) system is used. Particularly, a gold grating/polystyrene/platinum heterolayer structure was created. In our design, the gold grating ensures the excitation of the surface plasmon, the polystyrene acts as a dielectric spacer between metals, and the platinum layer is responsible for the catalytic function. The created structure was subsequently used for the water splitting half reaction (hydrogen evolution - HER), which was performed in the photoelectrochemical regime. The structure was also optimized from the theoretical and experimental points of view to reach the maximum efficiency in terms of hydrogen production. After optimization of the structure parameters, we observed a doubled increase in HER efficiency under illumination with light, which corresponded to the maximum of plasmon resonance absorption bands. The proposed nanoantenna design is favoured by the simplicity of preparation and the target area of use - the production of green hydrogen with the utilization of light (potentially, sunlight) energy. ACKNOWLEDGMENTS: This work was supported by the GACR under project 22-02022S.

Silicon (Si) is considered as one of the most promising anode-based materials for development of advanced Li-ion batteries (LIBs) due to its natural abundance and elevated theoretical specific capacity (3579 mAh/g). However, Si-based anodes face huge challenges that need to be solved before their possible commercialization in LIBs. The main drawbacks of Si are its low electrical conductivity and huge volume expansion (~300 %) during the charging and discharging process leading to mechanical damage of the whole anode material and to the capacity loss. Multiple strategies have been investigated to surmount them, among which promising advancements have been made with nanostructuring of Si. Nanostructuring strategy helps diminishing the volume expansion of Si nanoparticles and improves the Li ion diffusion. To overcome the poor electrical conductivity of Si, Carbon fillers are usually integrated into the Si-based anodes. Carbon provides the electronic pathway for electron transfer. Despite the fact that many of these Si/Carbon composite materials provide enhanced battery performance, there are still numerous issues that must be addressed. Some of these issues include the poor chemical compatibility of the carbon fillers (hydrophobic) with Si nanoparticles (oxidised surface), and with the polymer binder, leading to the formation of heterogeneous filler network, and hence non-continuous electronic pathways, which affect the overall electrochemical performance of the Si-based anode. In order to enhance the overall electrochemical performance of the Si-based anodes, we developed in this work unique tailor-made 1D nano-carbonaceous fillers of nanotubular morphology bearing nitrogen groups by carbonization of pre-synthesized nanostructured polypyrrole nanotubes (PP-NT), which were then integrated with Si nanoparticles using a simple and environmentally friendly strategy based on waterborne system. The morphology, physico-chemical properties, electrical conductivity and electrochemical performance of the subsequent Si-based anodes were investigated, and the structure-properties relationships were established.

Magnetron sputtered alumina thin films are widely used as protective coatings in various industrial applications. This work aims to demonstrate that sputtered alumina films possess different anti-corrosion properties than their bulk-crystalline counterpart. Alumina thin films were fabricated using pulsed DC reactive magnetron sputtering at varying operating pressures, ranging from 3 to 20 mTorr. The films were subjected to immersion in DI water at temperatures of 55 °C and 65 °C for a duration of 30 minutes. The study has shown that the sputtered alumina films created at operating pressures equal to or greater than 7 mTorr exhibited rapid reactivity with DI water, even under mild conditions. As-sputtered films had amorphous structures with varying degrees of porosity within the films. The calculated porosity was found to increase from 17% to 25% as the operating pressure increased from 3 to 20 mTorr, respectively. The hydroxide-containing functional groups on the surfaces of the alumina films suggested that the corrosion was driven by a hydrolysis reaction. The X-ray photoelectron spectroscopy (XPS) study highlighted distinctive features in both non-corroded and corroded sample groups. In the corroded group (7-20 mTorr), the O 1s peak intensities related to the hydroxide content were stronger than those associated with the lattice oxygen. The observed corrosion process may involve collective mechanisms, including the formation of soluble aluminum hydroxide complex species and Al-O bond breaking during proton transfer reactions between adsorbed water and hydroxide.

The development of electrode materials based on conjugated polymers for use in energy storage smart window (ESSW) applications attracted impressive interest in the last period due to some well-known advantages of polymers, including accessible synthetic route, low-cost processing, flexibility, high area coverage, and appealing redox characteristics. ESSWs enable both energy saving and energy storage, being exploited in modern buildings. Smart windows can modulate sunlight transmission by reversible color change based on electrochromism, contributing to lower electricity consumption. When electrochromism is integrated along with energy storage function, the smart window can also power small electronics. To improve the electrochemical performance of ESSWs, different strategies were developed so far, such as material structural design, material nano-structuring, doping, or material compounding [1]. Conducting polymers, as alternatives to metal oxide electrodes were progressively involved to obtain ESSWs. Among them, polyaniline, polypyrrole, and polythiophene derivatives were the most frequently used [2]. Poly(3,4-propylenedioxythiophene)s as polythiophene derivatives with lower oxidation potential, good chemical stability and electrical conductivity are potential candidates for use as electrodes in ESSWs. Pursuing this application, ProDOT-based polymers with electrochromic and pseudocapacitive behavior were developed. By molecular engineering of the side chain, the electrode nanostructure was tuned, with impact on ion diffusion and transport. To evidence the polymer’s potential for ESSWs, a detailed investigation was accomplished by various electrochemical methods. ACKNOWLEDGEMENTS: This work was supported by a grant of the Ministry of Research, Innovation and Digitization, CNCS-UEFISCDI, project no. PN-III-P4-PCE-2021-1728 (contract no. 46/2022), within PNCDI III. REFERENCES: [1] P. Yang, P. Sun, W. Mai, Electrochromic energy storage devices. Mater. Today, 19 (2016), 394-402.; [2] Z. Tong, Y. Tian, H. Zhang, X. Li, J. Ji, H. Qu, N. Li, J. Zhao, Y. Li, Recent advances in multifunctional electrochromic energy storage devices and photoelectrochromic devices, Sci. China Chem., 60 (2017) 13-37.

Pharmaceuticals represent an important class of emerging organic contaminants found in waters worldwide. Among the most widespread groups of such xenobiotics are analgesics and non-steroidal anti-inflammatory drugs (NSAIDs). To combat this problem, the development of advanced sorbents with higher sorption capacity, better selectivity and kinetics is essential. However, their limited recyclability and life-cycle are impending their overall applicability and sustainability.
This study uses tailored graphene derivatives (GDs) with different functionalities, which were capable of efficient sorption of paracetamol, ibuprofen, and diclofenac, reaching up to 1130 mg/g, 1010 mg/g, and 960 mg/g, respectively. The theoretical calculations revealed the critical role of polar functional groups in increasing the sorption capacity. Importantly, this study extends the applicability and life-cycle of the drug-loaded GDs to high performing electrodes for electrochemical energy storage in supercapacitors. After NSAIDs adsorption on the GDs, cyclic voltammetry demonstrated the emergence of redox peaks, which were absent in the pristine GDs. A substantially improved capacitance and energy storage ability from 9 to 29% was indicated for the drug-loaded GDs by galvanostatic charge/discharge, attributed to the redox-active NSAID functional groups. Electrochemical stability studies of the waste sorbents under continuous charging/discharging also revealed zero capacitance losses, pointing to the high affinity of the NSAIDs to the GDs under the specific operation conditions of the electrodes.
The present results underscore the potential of this strategy utilizing such GDs for sustainable environmental and energy technologies, complying with the European and United Nations’ goals for sustainable energy, waste reduction and circular carbon economy.

Phase change materials (PCMs) have been of interest to scientists for many years because of their ability to store thermal energy and wide range of potential applications. Sugar alcohols with a high energy storage capacity are particularly of interest [1]. These materials have almost twice higher latent heat of fusion than other organic materials [2], especially for PCM applications at higher temperatures. Unfortunately, the solid-liquid transition caused their tendency to leak during the phase transition processes, leading to limited thermal reliability of PCM systems. One of the ways to stabilize phase change materials could be their infiltration into porous carbon materials [3]. The main goal of our research was to obtain a phase change material with shape stabilization for long-term energy storage. For this purpose, sugar-alcohol-based PCMs modified with carbon modifiers such as nanotubes, graphene, were prepared and infiltrated into carbonized fruit peel. To characterize properties of the obtained PCM composites differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscope (SEM) were used. In addition, the percentage of PCM infiltrated into the carbonised fruit biomass was calculated. ACKNOWLEDGEMENTS: This work was supported from the subsidy of the Ministry of Education and Science for the AGH University of Science and Technology in Kraków (Project No 16.16.160.557). Research project partly supported by program „Excellence initiative - research university” for the AGH University of Krakow. REFERENCES: [1] R. Jia, et al., The Journal of Chemical Thermodynamics, 2017, 115, 233-248.; [2] S. T. Latibari, et al., Solar Energy, 2018, 170, 1130-1161.; [3] Y. Xu, et al., Fullerenes, Nanotubes and Carbon Nanostructures, 2019, 27, 289-298.

Phase change materials (PCMs) are a group of materials that is gaining more and more interest among scientists. Those materials are able to store and then release thermal energy during the phase change transition. Latent heat storage by PCMs is one of the most preferred forms of thermal energy excess storage. The incorporation of thermochromic properties into PCMs increases the system’s capabilities, which is able not only to store thermal energy but also to monitor or indicate temperature changes. It is important, especially in applications in temperature warning systems, which at the same time prevent further temperature increase. The boron nitride modifier is intended to improve the thermal conductivity of the phase change materials.
This work aimed to study the thermal, thermochromic, and structural properties of thermochromic phase change materials (TPSMs) with an inorganic modifier. Fatty acid, fatty alcohol, and bromocresol purple were used as thermochromic system components while boron nitride was used as an additive. Thermal properties were tested with thermogravimetry and differential scanning calorimetry analysis. Those results are essential in the case of phase change materials as they enable to determine thermal stability as well as temperature and enthalpies of phase change transitions: melting and crystallization. Also, FTIR was used to obtain data about the structural changes after PCMs modification. Thermochromic properties were examined by color determination graphics software as well as the thermal imaging camera.

This paper investigates the antimicrobial effect of geopolymer composites with metal microparticles (metal powder). The geopolymer matrix was modified with silver, copper, or nickel microparticles in the concentration of 1, 2, 3, or 4 %. The indirect observation included the leaching test, the Kirby-Bauer method, and the cultivating bacteria in a bioreactor with a geopolymer. The direct observation and analysis of bacterial growth were based on the print bacteria from the geopolymer surface on an agar plate or fluorescence assessment of bacterial viability with microscopy (so-called LIVE/DEAD™ BacLight™ bacterial viability Kit). Two types of bacteria cells were tested, Escherichia coli (gram-negative) and Micrococcus luteus (gram-positive). Our study aims to verify and compare different geopolymer composites' antimicrobial activity methodologies. Moreover, we uncovered the influence of the metal microparticle concentration (1-4%) as an additive in the geopolymer matrix.

Wearable biosensors for telehealth based on emerging materials and nanoarchitectonics needs the creation of safe, long-lasting, and flexible energy storage devices [1]. The integration of energy storage devices with biosensors is a fundamental component of self-powered wearables biosensors. In this context, we designed a wearable patch with a zinc-ion supercapacitor (ZISC) introducing a two-dimensional (2D) NiPS3 as a capacitive electrode made of a metal phosphorus chalcogenide. When coupled with graphene (creating NiPS3@graphene), the NiPS3 electrode's unique 2D nanosheet structure exhibits impressive electrochemical performance. We created a robust, flexible, and powerful device by imprinting the ZISC onto a cellulose substrate alongside NiPS3@graphene and zinc and integrating a hydrogel electrolyte. This device exhibits steady energy. This device's energy storage capabilities are consistent, with 86 % of its capacity remaining after 1,000 charge-discharge cycles. Furthermore, even when bent at varied angles, it shows good mechanical flexibility, retaining 97.7 % of its initial performance after 500 bending cycles. Finally, we've converted a small, lightweight ZISC tandem device into a self-powered biosensor mounted on a medically graded cellulose patch. This patch effectively powers both a temperature sensor and a glucose sensor, with Bluetooth connectivity allowing for real-time health monitoring. Our findings highlight the importance of 2D NiPS3@graphene-based zinc-ion supercapacitors as a component of patches for powering health monitoring systems [2]. REFERENCES: [1] Wearable sensors for telehealth based on emerging materials and nanoarchitectonics, J. V. Vaghasiya, C. C. Mayorga-Martinez, M. Pumera, npj Flex. Electron., 2023, 7, 26. https://doi.org/10.1038/s41528-023-00261-4 .; [2] Flexible energy storage patch based on NiPS3/graphene zinc-ion hybrid supercapacitor for integrated biosensors, K. K. Sonigara, J. V. Vaghasiya, C. C. Mayorga-Martinez, M. Pumera, Chem. Eng. J., 2023, 145204. https://doi.org/10.1016/j.cej.2023.145204.

With the advancement of the wearable electronics, there is a growing demand for the textile electrodes due to the their compliance and comfortableness to wear. Hence, a thorough investigation of suitable materials, fabrication methodologies and sensing elements needs to be carried out. While poplar trees are widely used in the wood industry, our group recently utilizate the poplar fiber in the production of nonwoven fabrics for the first time. In this study, an electricaly conductive web is formed via coating the poplar/polyester (PET) nonwoven fabric with silver nanowires (AgNWs). The coated poplar textile electrodes exhibited good electrical conductivity and superb flexibility. Therefore, they might have great potential to be used in wearable electronics as an ECG electrode.

We will present background and objectives of the recently started RenewPV COST Action (https://renewpv.eu), show the working group focuses and the workflow, current statistics of the RenewPV network, realized and planned events, short-term scientific missions (STSM) realized so far,as well as examples of recent scientific results obtained within the RenewPV collaborations. We will show opportunities for participations, such as international mobility, events and expert/facilities search, and related grants for supporting it.

Photocatalytic reduction of carbon dioxide to renewable fuel or other valuable chemicals using solar energy is attracting the interest of researchers, because of its great potential to offer a clean fuel alternative and solve the global warming problems. Unfortunately, the efficiency of CO2 photocatalytic reduction stays not very high. To develop an effective phototechnology for CO2 reduction, equal significance should be attributed to the foundational elements of photocatalysis: the photoreactor and the photocatalyst. The photocatalytic performance of the catalyst can be augmented through the incorporation of various dopant materials. These dopants should possess narrow band gaps, increased surface area, decrease recombination rate of charge carriers, and a greater number of active sites on the surface. These attributes can effectively contribute to the enhancement of photocatalytic activity. The efficiency of the photocatalytic reactor depends on the seamless interaction among reaction mixture, photocatalyst and light. The precise distribution of photocatalyst and light within the photocatalytic system holds the key to enhancing conversion and yield rates. Furthermore, comprehensive consideration must be given to all operational parameters, encompassing initial CO2 concentration, reaction duration, temperature, system pressure, pH, feed ratio, reducing agents, type of solvent, the wavelength of the light source, light intensity and activity decay over time during the photocatalytic CO2 reduction process. Clearly, modification of the semiconductor photocatalyst, optimizing operational parameters, and designing an appropriate photoreactor are pivotal factors in achieving efficient CO2 reduction for the production of sustainable hydrocarbon fuels.

Platinum group metals such as Pt, Ru, Pd, Ir, etc., have superior performance for various catalytic applications [1]. Due to their scarcity, efforts were being made to reduce the mass/loading or replace these noble metals. Atomic Layer Deposition (ALD) is one among the best technique to facilitate lowering of loading mass on a support of interest [2,3]. Due to the governing surface energy variations between noble metals and support surfaces, the growth initiates as nanoparticles (NP) and with a further increase in ALD cycles the agglomeration among NP’s dominates over the individual NP size increase, thus developing thin films of relatively higher thickness.
For electrocatalytic applications, it is important to choose the right substrates. Among available substrates, carbon papers and titania nanotube layers are best choices considering their physio-chemical properties, availability and low costs incurred.
The uniform decoration of these substrates by NPs of catalysts proved to be highly efficient in electrocatalysis, as shown in our recent papers [4,5].
The presentation will introduce and describe the synthesis of different noble metal NPs by ALD on important substrates. It will also include the corresponding physical and electrochemical characterization and encouraging results obtained in electrocatalysis.
REFERENCES: [1] Huang, Z. F. et al. Advanced Energy Materials vol. 7 (2017) 1700544.; [2] Yoo, J. E. et al. Electrochem. commun. 86, (2018) 6.; [3] Anitha, V. C. et al. J. Catal. 365, (2018) 86.; [4] Sitaramanjaneya M. Thalluri & Macak, J. M. Small (2023) 2300974.; [5] B. Bawab et al., Electrochim. Acta 429 (2022) 141044.

Laser ablation in liquids (LAL) has been developed into versatile technique producing various colloidal nanoparticles with applicable properties in e.g. biodetection, luminescence, SERS detection and photocatalysis. This contribution aims to present our recent research revealing novel advantages of LAL for catalytic purposes.
(1) The typical problems faced in the catalytic applications of colloidal nanoparticles is their instability towards aggregation, which decrease the catalytic properties. A strong effort is devoted to achieving the stability by various stabilizers which are, however, usually not environmentally friendly and such freely moveable nanocatalysts can enter biogeochemical cycles. LAL of FeS in water produces FeS-derived colloidal nanoparticles that absorb onto immersed porous ceramic substrates and create solar-light photocatalytic surfaces. The LAL thus offers simple and efficient way for the functionalization of porous surfaces by photocatalytic nanoparticles that precedes aggregation in the liquid phase.
(2) Moreover, LAL-induced FeS-derived nanoparticles contains high-pressure orthorhombic FeS phase which represent yet unreported example of high-pressure structures produced by LAL. High-pressure FeS exhibits significantly higher photocatalytic activity compared to its stable phase, which encourage next research of catalytic activity of LAL-induces high-pressure phases.
(3) Despite advanced research on functional colloidal inorganic nanoparticles and their reactivity, room-temperature reactive interactions between two different colloids have remained challenging so far. Simple room temperature mixing of ethanol TiO- and SiO-derived colloids allows the formation of TiSi2, which is the first case of room temperature reactive interactions between two colloidal species. Inclusion of TiSi2 in colloidal mixture significantly enhanced its photocatalytic efficiency for solar-light organics degradation.

Graphitic carbon nitride (g-C3N4) is one of the very promising metal-free photocatalysts with semiconducting properties that has been intensively studied during the last decade. Its important physico-chemical properties are high thermal, physical, and photochemical stability. G-C3N4 absorbs visible light as a result of the band gap energy of about 2.7 eV. It can be prepared by physical or chemical vapour deposition (PVD, CVD). However, a bulk synthesis from simple precursors by methods focused on the thermal condensation of nitrogen-rich precursors, such as cyanamide, dicyandiamide, melamine and so forth, allows for a high production at a low cost. However, in as-prepared state, it suffers from certain disadvantages, such as namely low specific surface area and fast recombination of photoinduced electron - hole pairs. They can be can be overcome by exfoliation [1], forming of heterojunction composites [2], and doping, for instance, with non-metal elements, such as sulphur, phosphorus [3], carbon, and oxygen [4]. Then, g-C3N4 can be used for various photocatalytic reactions, such as degradation of organic compounds, evolution of hydrogen, decomposition of nitrous oxide, reduction of carbon dioxide etc. This work summarizes some results of the photocatalytic applications of g-C3N4 obtained during last several years. ACKNOWLEDGEMENTS: This work was supported by Visegrad Fund (project No. 8F21007) and by VSB-Technical University of Ostrava (project No. SP 2023/034). The author also thanks the Large Research Infrastructure ENREGAT (project No. LM2023056). REFERENCES: [1] Svoboda L., Praus P., Lima M., Sampaio M., Matýsek D., Ritz M., Dvorský R., Faria J.D., Silva C.G., Materials Research Bulletin, 100 (2018) 322.; [2] Reli M., Huo P., Sihor M., Ambrožová N., Troppová I., L. Matějová L., Lang J., Svoboda L., Ritz M., Praus P., Kočí K., Journal of Physical Chemistry A, 120 (2016) 8564.; [3] Praus P., Smýkalová A., Cvejn D., Losertová S., Koštejn M., Novák V., Diamond and Related Materials, 130 (2022) 109439.; [4] Praus P., Smýkalová A., Foniok K., Novák V., Hrbáč J., Journal of Environmental Chemical Engineering, 9 (2021) 105498.

The importance to produce polymer-based membranes with suitable self-cleanable properties in preventing high risk of contamination on the fabric for long time usage has been becoming a relevant issues, especially in the last years when the pandemic outbreak of the Coronavirus disease (COVID-19) have brought to a mass consumption of personal protective equipment (PPE), such as face mask/respirators, which resulted in a potential source of further contamination from bacteria or virus. Modified electrospinning set-ups combined with modern textile techniques turned out to be an innovative way to manufacture nanofiber-based membrane showing high filtering performance against submicron pollution particles and suitable bioactive properties for tackling the current issues from bacterial contamination on PPE surfaces to the reusability of both disposable single use facemask and respirator’s filters [1].
With this paper we aim to provide further insight about the development of advanced electrospun nanofibrous photocatalytic membranes for large scale production. Investigation on the effects of processing variables on the fabrication of functionalized electrospun nanofibers embedded with active NPs for the scale-up line have been carried out by using Scanning Electron Microscopy and Energy Dispersive X-ray (SEM-EDX), Atomic Force Microscopy (AFM), and Raman spectroscopy analysis. In addition, photocatalytic disinfection for some bacteria strains, were conducted on the hybrid polymer-based membranes under UV-A light exposition by using the pristine electrospun membranes as control in the colony count method [2]. Finally, to provide a real perspective for the application of nanotextile in the manufacturing of advanced face mask on large-scale, both particle filtration and breathability test were also conducted on the nanofiber mats, in accordance with the standard required for Filtering Face Piece masks (FFP). REFERENCES: [1] Cimini A., E. Imperi, A. Picano, M. Rossi. Electrospun nanofibers for medical face mask with protection capabilities against viruses: State of the art and perspective for industrial scale-up. Applied Materials Today, 2023, (32) 101833.; [2] Q. Li, Y. Yin, D. Cao, Y. Wang, P. Luan, X. Sun, W. Liang, H. Zhu, Photocatalytic rejuvenation enabled self-sanitizing, reusable, and biodegradable masks against COVID-19, ACS Nano, 2021, 15 (7), 11992-12005.

The capture of solar radiation and generation of hydrogen via photoelectrochemical water splitting is considered one among the best solutions for renewable and sustainable energy production. Semiconductor materials are used as photon absorbers in photoelectrochemical cells. Tungsten oxide (WO3) is earth abundant and highly corrosion resistant in aqueous environments under various pH conditions, making it a promising material for water splitting photoanodes. Various distinct structures and morphologies of WO3-based photoanodes have been fabricated and studied to improve their photoconversion performance.
In this work, ammonium metatungstate hydrate (AMH) and polyvinyl alcohol (PVA) were used as electrospinning mixtures for the synthesis of WO3 nanofibers. Precursor concentrations and calcination temperatures were adjusted to achieve different nanofiber structures. TEM and SEM techniques were used to investigate the morphology of nanofibers. Absorbance and photoluminescence spectroscopy were employed to extract the information of energy band gap and electronic states within the gap. Photocurrent measurements using linear sweep voltammetry under AM 1.5 G illumination revealed the maximum photoconversion efficiency (PCE) of 2.08% obtained at the WO3 nanofibers prepared by using the AMH concentration of 5.6%w/v and calcination temperature of 900 °C. Analysis of structural morphologies and photoluminescence spectra provides the insights into the improved photoconversion efficiency and guidelines for the fabrication of robust water splitting photoelectrodes.

MXenes are a new type of nanoparticles, discovered in 2011 by Yu. Gogotsi, M. Barsoum et al. in Drexel University, USA. MXenes are hydrophilic, highly thermally and electrically conductive nanomaterials, with the ability to absorb light in UV-vis region, electromagnetic waves, etc. Polymer nanocomposites with MXenes nanofillers remain less studied comparing to other application fields.
In this work preparation and characterization of novel HAVOH/SWCNTs (single-walled carbon nanotubes), HAVOH/MXenes, HAVOH/SWCNTs/MXenes polymeric nanocomposites is reported. Highly amorphous poly(vinyl alcohol) (HAVOH) is a recently patented modified kind of poly(vinyl alcohol).
Composite samples were prepared with solvent casting method. The range of fillers load varied from 1.0 up to 5.0 wt. %. Structure, electrical, thermal and shielding properties of the prepared samples were studied. Highest electrical conductivity 7.9 × 10-5 S/cm was obtained for HAVOH/3.0 wt. % SWCNTs/2.0 wt. % MXenes. Structure study showed homogenous dispersion of the fillers within the matrix with possible formation of 3D conductive network. TGA results showed, that addition of carbon nanotubes and MXenes shifts the decomposition temperatures to higher values, thus slight stabilization effect of the HAVOH polymer is present. Using EMI-shielding analysis HAVOH/3.0 wt. % SWCNTs/3.0 wt. % MXenes revealed great total shielding effectiveness 55 dB, what is 122 times higher than for neat polymer. Prepared binary and ternary composites with are a promising basis for future preparation of the materials with many potential applications, including EMI-shielding, materials for flexible electronic, solar cells or supercapacitors.

ACKNOWLEDGMENTS
This work was funded by projects APVV-19-0465, and VEGA 02/0006/22 (Slovakia).

The effect of iron oxide nanoparticles on the surface properties of mesoporous spherical silica was investigated. The nanoparticles affect the electrical potential on the silica surface, especially at acidic pH, when the Debye length becomes comparable to the average pore size. This leads to the merging of ion layers formed around the iron oxide nanoparticles inside the pores, and pore entrances effectively begin to act as anchored centers of positive charge at acidic pH. As a result, more silanol groups on the outer surface of the silica are deprotonated by electrostatic interactions. In the range of pH between 3.5 and 6.5, this causes a radical change in the Zeta potential value of spherical silica gel and a significant change in its adsorption properties. The latter was confirmed experimentally for an aqueous solution of methylene blue. ACKNOWLEDGEMENTS: The authors acknowledge the financial support from the program of the Polish Ministry of Science and Higher Education under the name "Regional Initiative of Excellence" in 2019 - 2023, project no. 003/RID/2018/19, funding amount 11 936 596.10 PLN.

The influence of pulsed substrate bias on the structure, microstructure and size of crystals of Tix-1AlxN coatings grown by cathodic arc deposition was investigated. Tix-1AlxN coatings were deposited on cemented carbide substrates with -30 V, -60 V and -300 V pulsing bias (duty cycle 10 %) and varying compositions. The pressure in the chamber was 4.5 Pa (N2). Three types of coatings with specified Al/Ti ratio were manufactured (the average ratio Al/(Ti+Al) in the coatings was 0.25, 0.5, 0.55). According to XRD results Tix-1AlxN coatings have the typical cubic B1 structure (NaCl-structure) independently of chemical composition. All deposited coatings have columnar structure. Coatings grown at -30 V and -60 V pulsed bias have texture [111]. The strong [111] texture can be attributed to a kinetically driven mechanism influenced by the relative flux of ion species, which affects the surface migration of adatoms during grown. In comparison of coatings made with -30 V and -60 V bias, coatings made with -300 V pulsed bias had less preferred orientation. The transition to [100] orientation with increased ion energy is in agreement with the fact that the [111] direction exposes the densest array of atoms to the ion beam while the [100] is the most open channeling direction. Defects and composition was not affected by pulsing voltage, but surface roughness was highest (Sa≈0.17…0.22 µm) for coating deposited at pulsed bias -30 V.

Two-dimensional transition metal dichalcogenide (2D-TMD) nanostructures have received increasing attention in the field of electrochemistry due to their layered structure. The physical and electrical properties of the 2D-TMDs are highly attributed to their number of layers. Recently, various approaches have been applied to modify the 2D-TMD materials to control their structures and subsequently their properties to extend their performance in electrochemical applications. Among them, the conducting polymer (CP)-templated approach has been considered as an efficient way to prepare of 2D-TMD hybrid nanostructures. CPs can be used as a conductive template to accommodate more TMD layers, resulting in more catalytic active sites for electrocatalytic applications. In this work, two different TMD (MoSe2 and WSe2)-based nanostructures were prepared in the presence of different CPs and simultaneously doped with transition metal particles (Co, Ni, or Fe) by a facile hydrothermal method. The resulting nanostructures were used as electrocatalytsts in alkaline water splitting reactions, including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The overall water splitting performances of the 2D-TMD nanostructures were also carried out in alkaline solution. It was found that the incorporation of CP and transition metal doping enhanced the catalytic activities of the resulting electrocatalysts in both the HER and OER. Furthermore, this work provides new insights into the design of efficient 2D-TMD-based electrocatalysts with bifunctional activities for HER and OER.
ACKNOWLEDGEMENTS: This work received funding from the European Union ́s Horizon 2020 Research and Innovation Programme under the Programme SASPRO 2 COFUND Marie-Sklodowska-Curie grant agreement No. 945478 and from project VEGA 02/0006/22 (Slovakia).